Sensor workAssociate Professor of Chemistry Elizabeth Harbron (center) checks on the progress of one the undergraduate research groups she mentors. Desmarie Sherwood '13 (left) and Clare LeGuyader '11 are working on a photochemical sensor to detect the presence of mercury in water.
Photo by Joseph McClain

William & Mary’s Elizabeth
Harbron is one of six U.S. chemists to be named Henry Dreyfus Teacher-Scholars.
The award recognizes chemistry faculty who not only are accomplished
researchers themselves, but who also incorporate undergraduate students into
their research.

“Research support at
undergraduate institutions is very important,” states Mark J. Cardillo,
executive director of The Camille and Henry Dreyfus Foundation, in a press
release announcing the awards. “Nearly half the chemists who earn a doctorate
degree receive their bachelor’s degree from an undergraduate institution. And
research is a fundamental part of chemistry education.”

The Henry Dreyfus
Teacher-Scholar Award carries a $60,000 unrestricted research grant for each
recipient. Harbron, associate professor in William & Mary’s Department of
Chemistry, will use the grant to pursue research into a number of rhodamine
spirolactam dyes, molecules that show promise in applications as fluorescent sensors.
The projects involve a number of William & Mary students.

“This research is based on some
molecules we started playing with a little over a year ago in my lab. Like
other molecules we use in my lab, these have two forms,” she explained. “In one
form they are completely white—essentially colorless. But when they come into
contact with the right stimulus —this could be acid or a metal ion—then they
undergo a molecular transformation that causes them to become incredibly
brightly colored and fluorescent. ”

The Dreyfus award will allow
Harbron and her lab to investigate two different aqueous sensor projects. “Any
time you have something colorless until it meets something else, you have the
potential for a sensor,” she says. One project is focusing on spirolactams that
could be used, in concert with some polymer nanoparticles, to detect the
presence of mercury in water.

Undergraduates
in the lab

Clare LeGuyader ’11 has been
working in Harbron’s lab synthesizing new rhodamine spirolactams that respond
to mercury ions for her chemistry Honors research. Harbron says Desmarie
Sherwood ’13 is learning the ropes so she can take over after LeGuyader
graduates. The mercury project also includes Beth Childress ’12, who makes the
polymer nanoparticles that are the other component of the mercury sensor
system. Harbron notes that the nanoparticles used in the mercury sensor project
were originally pioneered in her lab by Christina Davis ’10.

The idea is to investigate
the potential for a sensing device that would indicate the presence of
increasing concentrations in water by the colors and fluorescence of the
spirolactam dyes reacting with the mercury ions dissolved in the water. Harbron
says that the activated molecules range in color through various pinks and
purples, including fuscias, magentas and other highly distinguishable shades.
The second program centers on developing a spirolactam-based sensor system to
determine pH, or the relative acidity/alkalinity of water, through a change of
color. “In theory, you could line up several of these and have a large
variation of fluorescent color over a small pH range,” she explained.

“Becca Allred ’10 was the
first student in my lab to begin working with rhodamine spirolactam dyes as pH
sensors,” Harbron said. “She used them as part of her 2009-2010 Honors project,
and her results were interesting enough that I wanted to keep working with the dyes
after she graduated.”

Courtney Roberts ’11
essentially took over the project after Allred graduated, although Harbron
noted the work has “changed and mutated as we have learned more about the dyes
and how to make them and work with them.” Roberts is continuing the work on the
pH-responsiveness of the dyes as part of her Honors research.

11
students as coauthors

Harbron, associate professor
in the William & Mary Department of Chemistry, was nominated for the award
by department Chair Christopher Abelt. In his letter of nomination, he pointed
out that Harbron’s research group is the most popular among students
concentrating in chemistry at William & Mary.

“Prof. Harbron
incorporates many student coworkers into her research projects,” Abelt wrote.
“Eleven students have appeared as coauthors on her publications. On average,
four students graduate from her lab each year. Since most of her students work
with her for at least four semesters, she mentors nearly ten students
researchers over the academic year.”

In support of her nomination,
Harbron put together a summary of the her research as well as a funding
proposal for the spirolactam projects. Her lab had already been working on
aspects of the work, and she says that she and the students have established proof
of concept, “but we want to get further along before we publish it.” She noted
that Roberts and LeGuyader worked together on the mercury-responsive dyes in
her lab throughout the summer of 2010.

“This award is really a
testimony to the accomplishments of my students,” she said. “Beth, Courtney,
and Clare were responsible for obtaining the preliminary data that went into
the grant proposal.”

Harbron is also the interim
director for William & Mary’s Murray Scholars Program, an initiative that
recruits the nation’s best high school students to William & Mary for a set
of closely mentored research-based experience. She won a CAREER award
from the National Science Foundation (NSF) in 2007. Her work has been featured in
Ideation magazine and in the NSF’s
partner web site, LiveScience.

The Camille and Henry Dreyfus
Foundation is a leading non-profit organization devoted to the advancement of
the chemical sciences. It was established in 1946 by chemist, inventor, and
businessman Camille Dreyfus, who directed that the foundation’s purpose be “to
advance the science of chemistry, chemical engineering and related sciences as
a means of improving human relations and circumstances around the world.”